I have found out that it's not forgetting the flash drives. It's switching source. If you tap the source button on the left side or screen it will switch right back to usb and you don't have to unplug it. So something in there is telling it to do this. Mine wasn't doing it until today. I went through every setting this morning and changed everything to how I wanted it. So the problem started happening after I did that. I will try and go through the settings again tomorrow and set things back to default and see if the issue goes away. I'll let you guys know. Unless someone else wants to try that tonight. It might just be a coincidence but I dunno.